1. Field of the Invention
The present invention relates to information handling systems and methods and, more particularly, to information handling systems and methods including methods for loading and linking libraries of accessory programs and data.
2. Prior Art
In information handling systems where a kernel of an operating system is stored in a read-only memory (ROM), it is desirable to minimize the area (footprint) of the ROM on the integrated circuit carrying the ROM. In the prior art, all machine readable or executable programs including dynamically linked programs and shared libraries are preloaded into the ROM to create the embedded system.
In a system where the industry standard Executable and Linking Format (ELF) is employed, it is desirable to store the machine readable and executable programs and libraries without storing ELF information. One issue presented by eliminating the ELF information from the ROM is that dynamically linked ELF machine readable files are generally not loadable from an external device to use the preloaded shared libraries.
An embedded system is needed which would provide a smaller area for the ROM by preloading shared libraries in the ROM but with a mechanism for dynamically loading ELF machine readable files from a source outside of the ROM.
Accordingly, a method and means for enhancing an embedded system includes generating shared library information which is stored in the ROM, the shared library information including pointers to structures for each shared library to be preloaded into the ROM, maintaining each module per library as a linked list, writing the structures describing the preloaded libraries into the ROM image when the ROM image is generated, and as pointers to the structures are not valid in the ROM image, relocating the pointers to these modules so that they are valid in the loader""s address space when remapped into a loader by the kernel.
At system start-up or xe2x80x9cboot,xe2x80x9d the kernel starts the embedded loader and maps the structures exactly where the loader expects to find them. Thus, when the loader attempts to load an external dynamically linked ELF executable file that is linked to one of the shared libraries in the ROM, the loader resolves all references to the preloaded library by traversing the structures provided that were mapped into its address space by the system kernel.
It is an advantage of the present invention that the size of the read-only memory in an embedded system may be minimized by allowing dynamically linked programs and shared libraries without the need for the read-only memory to contain all of the ELF information.